Practice question · Put in order
Put the steps for computing a standard deviation in the correct order.
- Compute the mean of the data set.
- Take the square root of the variance to get the standard deviation.
- Average the squared deviations to get the variance.
- Square each deviation.
- Subtract the mean from each value to get its deviation.
Hints
- You cannot measure distance from the mean until you know the mean.
- Squaring comes before averaging; the square root is the very last step that returns to original units.
Show the answer
- Compute the mean of the data set.
- Subtract the mean from each value to get its deviation.
- Square each deviation.
- Average the squared deviations to get the variance.
- Take the square root of the variance to get the standard deviation.
Why
Mean first, then deviations, then square them, average to variance, and finally square-root back to the standard deviation. Squaring before averaging is what prevents positive and negative deviations from cancelling to zero.
Practise Descriptive Statistics
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